Patient monitoring system with gatekeeper signal

ABSTRACT

A gatekeeper electronic signal can be generated by a patient sensor and/or in an intermediate device, such as an electrical cable, that is separate from a patient&#39;s physiological information electronic signal. The gatekeeper signal can be generated to indicate to a computer monitor that the sensor and/or cable is of the type that is compatible with, and/or usable with, such computer monitor, and/or that the sensor and/or cable is properly attached to the computer monitor. The gatekeeper signal can be created by an ambient temperature sensor on, or in electrical communication with, the patient monitor, and/or the gatekeeper signal can be created by a gatekeeper electronic signal generator to simulate an ambient temperature value. The gatekeeper signal can be separate from an electronic signal or plurality of signals that include patient physiological information, and the gatekeeper signal may not include any patient physiological information.

RELATED APPLICATIONS

This application is a U.S. National Phase of PCT/US2015/017377, whichclaims priority to U.S. Provisional Patent Application No. 61/944,408,filed on Feb. 25, 2014, and entitled, “Patient Monitoring System withGatekeeper Signal,” the entire contents of which are hereby incorporatedby reference herein and made part of this specification for all that itdiscloses.

BACKGROUND

Field

Certain embodiments disclosed herein relate generally to monitoringphysiological parameters of a patient, and specifically to verifyingthat a proper sensor is in communication with a physiological monitoringsystem.

Description of the Related Art

In many healthcare settings, especially in the care of seriouslyafflicted cardiac patients, it is desirable or necessary for ahealthcare practitioner to be able to obtain generally continuousinformation about a patient's physiology, such as a patient's cardiacperformance or a patient's blood characteristics. Electronicphysiological monitoring systems can include a tubular catheter insertedinto a patient's blood vessel, a sensor in fluid communication with thecatheter, and a computer monitor in electrical communication with thesensor. The computer monitor is typically positioned at or near apatient's bedside and typically includes a computer processor and adisplay of data regarding the patient's cardiac performance.

The sensor may be a disposable component, used in treating a particularpatient and then discarded and replaced with a new sensor. A variety ofdifferent types of sensors are made by different sources and purchasedby healthcare facilities for different physiological monitoring systems.Several of these different types of sensors may be available in aparticular healthcare setting. In addition, some sensors may beconnected to the monitoring systems by one or more intermediate devices,such as one or more cables, that may be disposable or non-disposable.Some sensors and/or intermediate cables may not be validated for, orcompatible with, or safe for use with, a particular physiologicalmonitoring system. Such sensors and/or cables, if somehow connected toor placed in electrical communication with a particular physiologicalmonitoring system, might cause damage to the monitoring system or yieldfalse readings about a patient's current physiological condition.Moreover, even if a proper sensor and/or cable is intended to be used,but the electrical connection between the sensor and/or cable and thecomputer monitor is not properly connected, such as if the electricalconnector is not fully inserted or includes a bent or damaged electricalcontact, then an incomplete or faulty data signal may be transmittedfrom the sensor to the computer monitor.

SUMMARY

In some embodiments, a gatekeeper electronic signal can be generatedremote from the patient monitor. In some embodiments, the gatekeeperelectronic signal can be generated by a patient sensor and/or in anintermediate device, such as an electrical cable, that is separate froma patient's physiological information electronic signal. The gatekeepersignal can be generated to indicate to a computer monitor that thesensor and/or cable is of the type that is compatible with, and/orusable with, such computer monitor, and/or that the sensor and/or cableis properly attached to the computer monitor. In some embodiments, thegatekeeper signal can be created by an ambient temperature sensor on, orin electrical communication with, the patient monitor, and/or thegatekeeper signal can be created by a gatekeeper electronic signalgenerator to simulate an ambient temperature value. The gatekeepersignal can be separate from an electronic signal or plurality of signalsthat include patient physiological information, and the gatekeepersignal may not include any patient physiological information. In someembodiments, the gatekeeper signal is not configured to be used toprocess or evaluate any electronic signals to obtain or analyze patientphysiological information.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a critical-care patient monitoringsystem;

FIG. 2 illustrates an example of a schematic representation of a patientsensor that is configured to generate a gatekeeper electrical signal;

FIG. 3 illustrates an example of a patient sensor with an ambienttemperature sensor; and

FIG. 4 illustrates an example of an algorithm or subroutine in acomputer monitor for monitoring, evaluating, and/or responding to agatekeeper electrical signal.

DETAILED DESCRIPTION

As illustrated in the example of FIG. 1, in some embodiments, acritical-care patient monitoring system 100 can include a computermonitor 110 placed in electrical communication with a patient sensor120, such as a cardiac-monitoring sensor and/or a blood parametersensor, which in turn is placed in fluid communication with a bloodvessel of a patient 130, such as by way of a catheter 150. Though shownas an integrated unit, the computer monitor 110 may include one or moreseparable components; for example, the visual display, with or withoutembedded processing capabilities, may be releasably attached to the basecomputer monitor. As a patient's heart beats, a pressure wave istransmitted through the patient's interconnected system of blood vessels(veins and arteries). The pressure wave provides information about thepatient's cardiac performance, which can be electrically transmittedfrom the patient sensor 120 to the computer monitor 110, such as by wayof a wired connection 160 or a wireless connection. The informationabout the patient's cardiac performance can be derived or calculatedthrough a mathematical analysis performed by the computer monitor 110 ofthe shape of the pressure wave, and/or the ways in which the pressurewave changes over time, etc. As shown, the patient sensor 120 can bepositioned on a suitable holding structure 140, such as a pole stand orother holder, and the patient sensor can be in fluid communication witha liquid source 170.

As shown in FIGS. 2 and 3, in some embodiments, a patient sensor 120such as a cardiac monitoring sensor can comprise a transducer 180 thatis configured to transform mechanical motion into electrical energy,such as a pressure sensor that produces an electrical signal thatchanges over time in response to changes in fluid pressure. The patientsensor 120 can comprise a fluid-receiving region 190, such as a fluidchannel, that is in communication with the transducer. The fluid channelcan form part of, or be attached to, or otherwise be positioned in fluidcommunication with, the medical catheter 150 or other tubing or devicein fluid communication with a patient's vessel. In some embodiments, thefluid-receiving region 190 is a liquid-receiving region that isconfigured to receive one or more liquids such as blood, water, saline,or another medical fluid. A distal end of the medical catheter can beinserted into a patient's blood vessel, in contact with the patient'sblood, in a conventional manner.

The medical catheter 150 can contain a column of biocompatible fluid,such as saline and/or blood, that interfaces with the blood flowinginside of a patient's blood vessel (e.g., a vein or an artery). Thecolumn of fluid can be provided by a liquid source 170, such as an IVbag, that is pressurized or that is gravity-fed into the patient sensor120, which can be disposed in fluid communication with the patientsensor 120 by way of one or more fluid connectors 195. A suitable valve,such as a stopcock 200 can provide a controllable connection between theliquid source 170 and the patient sensor 120. The stopcock 200 canpermit fluid to flow from the liquid source 170, to the fluid-sensingregion 190, and/or to or from a side port 205. As the pressure wave fromthe patient's beating heart is transmitted through the patient's bloodvessel, the wave is communicated through fluid interaction with theblood into the column of fluid inside the medical catheter 150, and thento the fluid channel 190 at or near the transducer, where the fluidpressure wave can be converted into a cardiac monitoring electricalsignal and transmitted by an electrical wire 160 or wirelessly to thecomputer monitor 110. The computer monitor 110 can be programmed toanalyze the cardiac monitoring electrical signal to providephysiological information about the patient, such as cardiac performanceinformation (e.g., pulse rate, blood pressure such as systolic pressureand/or diastolic pressure, and/or cardiac output, etc.).

In addition to, or instead of, providing cardiac performanceinformation, a blood parameter sensor can be provided with a medicalcatheter configured to convey information about one or more bloodparameters, such as one or more of: a blood gas level (e.g., oxygenand/or carbon dioxide, etc.), a pH level, a hemoglobin level, ahematocrit level, a glucose level, and/or a blood temperature, etc. Insome embodiments, one or more blood parameters can be determined bymeasuring characteristics of light waves that are transmitted intoand/or reflected from the blood or another substance in communicationwith the blood, such as through a system of one or more fiber opticlight-transmitting and/or light-receiving cables. In some embodiments,one or more blood parameters can be determined by placing one or moresensors in close communication with the blood, such as atemperature-sensing thermistor suspended in the blood or positioned nearthe blood.

The patient sensor 120, whether a cardiac-monitoring sensor and/or ablood-parameter sensor, or some other form of patient sensor, can bestructured, positioned, and/or oriented in a variety of different ways.The patient sensor 120 can comprise a patient-information electricalsignal generator 210. In some embodiments, a physiological sensingdevice such as a cardiac monitoring sensor and/or a blood parametersensor can form part of the patient-information electrical signalgenerator or can be in electrical communication with thepatient-information electrical signal generator.

In some embodiments, the patient sensor 120 comprises a housing 230 withone or more transducers 180 or receivers positioned on or in or near thehousing 120, in combination with a medical catheter 150 and one or moreelectrical wires 160 and/or one or more electrical connectors 240. Thepatient sensor 120, including the physiological sensing device ortransducer 180, the patient-information electrical signal generator 210,the gatekeeper electrical signal generator 250, the medical catheter150, the electrical wires 160, and/or the electrical connectors 240, canbe a disposable unit. A patient-information electrical signal can beproduced by the patient-information electrical signal generator of thepatient sensor from the patient information or data obtained by one ormore sensors regarding the physiological characteristics, conditions, orstatus of a patient. The patient's physiological information can beconveyed to or toward the computer monitor 110 of the critical-carepatient monitoring system 100 by way of a patient-information electricalsignal through the one or more electrical wires 160, 260 and/or one ormore electrical connectors 240. In some embodiments, the patient'sphysiological information can be conveyed to or toward the computermonitor 110 of the critical-care patient monitoring system 100 by way ofa patient-information electrical signal that is transmitted wirelessly.

In some embodiments, a non-disposable electrical cable 260 can be usedto convey the patient-information electrical signal and the gatekeeperelectrical signal from the electrical wires 160 in the patient sensor120 to the computer monitor 110. In some embodiments, a gatekeepersignal-generating device 250 can be in electrical communication withsuch a cable or another intermediate device, or can be integrated intoor embedded in such a cable or another intermediate device, instead ofor in addition to being in electrical communication with or integratedinto or embedded in a disposable patient sensor 120. In some healthcaresettings, the distance between the transducer portion 180 of the patientsensor 120 and the computer monitor 110 can be significant, such as whenthe transducer 180 is positioned on a pole stand 140 or in some otherlocation relatively close to the entry point of the medical catheterinto the patient's body (such as into the patient's arm 130 or someother location) and the computer monitor 110 is located on a stand in ahospital room several feet away from the entry point, A fluid 145catheter attached to the patient can be connected to the fluid line 150from the sensor 120 by way of a pair of fluid connectors, such ascorresponding male and female fluid connectors 155, 175.

Since the electrical wiring may be draped down from the transducer 180,across the floor, and back up to the computer monitor 110 (to avoidcreating horizontal wire barriers to persons walking around thepatient's vicinity), the length of electrical wiring 160, 260 betweenthe transducer 180 and the computer monitor 110 may be in the range ofabout 6 feet or so (2 meters). If all of this wiring 160,260 were partof the disposable patient sensor 120, it would dramatically increase themanufacturing cost and unit price of the disposable patient sensor 120,which would be unnecessary because much of the wiring does not routinelycome into contaminating contact with a patient, and need not be sterile,but is instead positioned on the floor or near the computer monitor, andcan therefore be used with multiple patients. In some embodiments, theelectrical connection with the patient sensor 120 is achieved byattaching an electrical connection portion 240 of the patient sensor 120to a proximal electrical connection portion of the non-disposable cable,and then attaching a distal connection portion of the non-disposablecable 270 to an electrical connection portion of the computer monitor.

The electrical information can be conveyed in some embodimentswirelessly, such as by way of an electromagnetic short-range signal,such as over a WI-FI® network or by way of a BLUETOOTH® signal or aZIGBEE® signal, or by some other wireless protocol that is acceptable orutilized in a healthcare setting. Any description or illustration inthis specification of an electrical wire 160, 250, or electricalconnection 140 can be accomplished in a wireless manner and suchdescriptions or illustrations of wires or electrical connections shouldbe understood to also refer to and encompass wireless connections. Forexample, any description or illustration of a patient-informationelectrical signal and/or a gatekeeper electrical signal being conveyedover a wired connection should be understood to also refer to andencompass a suitable wireless connection.

To help verify that a proper patient sensor 120 is attached to thecomputer monitor 110 and/or that a proper secondary cable 270 isattached to the computer monitor 110 and/or to ensure that theelectrical connection between the sensor 120 and the computer monitor110 is properly established, a gatekeeper electrical signal can betransmitted to the monitor 110. In some embodiments, the signal isgenerated by a component permanently coupled to the sensor device. Insome embodiments, the signal is generated at least in part by thenon-disposable cable configured to place the sensor in electricalcommunication with the computer monitor. In some embodiments, the signalis generated by a combination of both the components permanently coupledto the sensor device and the non-disposable cable configured to placethe device in electrical communication with the computer monitor. Insome embodiments, the receipt of the gatekeeper electrical signal by thecomputer monitor is a required condition for the computer monitor 110 tofunction and/or for the computer monitor 110 to display patientinformation on a display screen 280. In some embodiments, the monitor110 will only calculate and display physiological information about thepatient after the monitor 110 receives the gatekeeper electrical signaland/or only for so long as the gatekeeper electrical signal continues tobe transmitted to the monitor (continuously or within an allowable timeinterval). In some embodiments, if the gatekeeper electrical signal isnot received by the computer monitor as expected, an error message willbe conveyed on the display screen or in some other manner. The errormessage can indicate that no sensor is connected, that an impropersensor is connected to the computer monitor, and/or that the user shouldcheck an electrical attachment with the computer monitor, etc.

The gatekeeper electrical signal can be generated by a signal generatorin a variety of different ways and in a variety of different locations.As shown in the example of FIG. 2, in some embodiments, the signalgenerator for producing the gatekeeper electrical signal is located onor within or near the housing 230 of the patient sensor. In someembodiments, the gatekeeper electrical signal is produced by a signalgenerator comprising a temperature sensor 290, such as an ambienttemperature sensor. In some embodiments, the signal generator is only anambient temperature sensor; in some embodiments, a temperature sensor290 is in electrical communication with a gatekeeper electrical signalgenerator for producing the gatekeeper electrical signal. Thetemperature sensor 290 can be structured, positioned, and/or oriented ina variety of different ways. For example, the temperature sensor 290 cancomprise a temperature-sensitive electrical component, such as a diodeor a transistor or a thermistor or another electrical component, inwhich the output voltage or another quality of the electrical signal orthe resistivity of the component changes as a function of thetemperature of the air or other material surrounding the electricalcomponent that is in thermal communication with thetemperature-sensitive electrical component.

It is expected that the critical-care patient monitoring system 100 willbe used in settings in which the ambient temperature is generally aboutthe level of a standard room temperature, such as about 70° F. or about21° C., and/or within a standard room temperature range, such as atleast about 65° F. and/or less than or equal to about 75° F. (or atleast about 18° C. and/or less than or equal to about 24° C.). Othertemperature ranges, including other standard room temperature ranges,within or outside of these temperature ranges can be utilized. Thetemperature sensor 290 can be configured to generally sense the ambienttemperature in the patient's room or the ambient temperature at, near,or inside of the patient sensor 120 or the housing 230 of the patientsensor 120. In some embodiments, the gatekeeper temperature sensor 290is positioned outside of the fluid-containing portion 190 of the patientsensor 120 and/or outside of fluid communication or direct thermalcommunication with the fluid in the patient sensor 120. In someembodiments, the gatekeeper temperature sensor 290 is isolated orseparated from, is largely unaffected by, and/or is unable to provideclinically useful information about, changes in a patient's bodytemperature or other physiological parameters of a patient. In someembodiments, the gatekeeper electrical signal can help ensure that thecritical-care patient monitoring system is used in an environment inwhich ambient temperature ranges will not affect the functioning of theelectrical equipment and/or the physiological readings obtained from apatient.

In some embodiments, the gatekeeper electrical signal generator 250 isin electrical communication with the gatekeeper temperature sensor 290.The gatekeeper electrical signal generator can comprise an electricalcircuit configured to produce a gatekeeper electrical signal in concertwith the gatekeeper temperature sensor 290. In some embodiments, theelectrical signal produced by the gatekeeper electrical signal generator250 varies as a function of the ambient temperature sensed by thetemperature sensor 290. In some embodiments, the electrical signalproduced by the gatekeeper electrical signal generator 250 is agenerally constant value so long as the temperature sensed by thetemperature sensor 290 is within a predetermine range, such as within apredetermined range of standard room temperatures.

The gatekeeper electrical signal can be conveyed from the gatekeeperelectrical signal generator 250 (located on or in the patient sensor120, in some embodiments) to the computer monitor 110 of thecritical-care patient monitoring system 100 by way of an electrical wire165 that is separate from the electrical wire or wires 167 configured toconvey the patient-information electrical signal. The electrical wires165, 167 can be separately insulated and bound together in a common wirebundle 160. In some embodiments, the gatekeeper electrical signal isindependent from the patient-information signal and does not include anyinformation about the physiological status or condition of a patient.

In some embodiments of patient sensors, the gatekeeper electrical signalis not produced from or using an actual temperature sensor or atemperature value, but instead creates a simulated temperature signalusing an electrical signal generator. In FIG. 2, the connection betweenthe temperature sensor 290 and the gatekeeper electrical signalgenerator is represented by a dashed line to demonstrate that it neednot exist in some embodiments because there may not be a temperaturesensor 290 at all. A gatekeeper electrical signal derived from asimulated temperature is not based upon a temperature reading and maynot vary at all, or may not vary appreciably, according to changes intemperature. The patient sensor 120 may not include a temperature sensorat all, at least not an ambient temperature sensor. The simulatedtemperature signal may be utilized in situations where the room orambient temperature is not expected to be outside of any range thatwould affect the proper functioning of the electronic components or thepatient's physiological condition; or where there is little or no riskof sensor misattachment or a mix-up in the type of sensor to be used; orwhen it is desired to produce a simpler sensor with less electroniccomplexity. The gatekeeper electrical signal produced with a simulatedtemperature signal can be configured to be generally in the same rangeas the signal that would ordinarily be produced and transmitted by atemperature-sensing gatekeeper or verification signal generator.

A supplier can provide a disposable patient sensor 120, or anintermediate device, such as an electrical communication wire or cable,for use with a computer monitor 110, that is configured to provide agatekeeper signal to the computer monitor 110. The supplier can provideinstructions to a healthcare provider, or other user, to electricallyconnect the sensor and/or the intermediate device, to a computer monitor110 that is configured to monitor an electrical gatekeeper input portfor an electrical gatekeeper signal. The sensor may or may not actuallyprovide a gatekeeper signal that is representative of a truetemperature; rather, the gatekeeper signal may be a real or simulatedsignal. The supplier can provide instructions to the user to removeand/or discard the sensor after use by a patient, such as in a biohazardreceptacle.

The computer monitor 110 of the critical-care patient monitoring system100 can comprise a computer processor, a computer display 280 configuredto display physiological information about the patient (including one orany combination of any of the physiological information that the patientsensor is configured to obtain), a power source (such as a battery or apower cord), and one or more electrical connectors, 270, 240 configuredto establish an electrical connection with the patient sensor, such asby way of an attachment with one or more electrical connectors 240 thatform part of the patient sensor. The computer monitor 110 can beconfigured to receive one or more patient-information electrical signalsthat convey information about a patient's physiological conditions. Oneor more components of the computer monitor 110 may be releasably coupledto the other components of the monitor. For example, the display 280 maybe detachable from the base. The display 280 may include the computerprocessor and other electrical circuitry used in processing the signals,or the processor may be included in other components of the monitor 110.

The computer monitor 110 also can be configured to receive a gatekeeperelectrical signal. In some embodiments, the computer monitor 110 isconfigured to receive, process, calculate, and/or identify an ambienttemperature value from the gatekeeper electrical signal, which can be anactual ambient temperature value or a simulated ambient temperaturevalue.

As schematically illustrated in an example in FIG. 4, block 300 showsthat the computer monitor 110 can monitor the gatekeeper signal orverification signal, such as on a generally continuous basis, checkingperiodically whether a gatekeeper signal or verification signal has beenreceived, as shown in block 310. If some type of electrical signal hasbeen received by the monitor 110 at the gatekeeper signal electricalconnection, then the computer processor of the monitor 110 can beconfigured to analyze the signal, as shown in block 320, to determinewhether the signal is within a particular range of values, or exhibits aparticular shape or variance over time, and/or demonstrates any otherparticular characteristics that the computer processor of the monitor110 is programmed to recognize as indicative of a gatekeeper signal(such as either an actual temperature signal or a simulated temperaturesignal), as shown in block 330.

In some embodiments, as illustrated in block 340, the computer monitor110 can be programmed to enable receipt of the patient informationsignal, processing of the patient information, storage of the patientinformation signal in memory, transmission of the patient informationsignal, and/or display the patient information, only after, and/or onlyfor so long as, the gatekeeper electrical signal is transmitted to thecomputer monitor. In some embodiments, the computer monitor 110 receivesthe gatekeeper signal from the patient sensor 120 and compares it to apredetermined range of values, thus determining whether the ambienttemperature sensed by the patient monitor is within a predeterminedrange of ambient temperatures, such as a predetermined range of standardroom temperature values. As shown in block 350, if the signal receivedat the gatekeeper signal electrical connection on the monitor 110 isdetermined not to be an actual or simulated temperature signal, then themonitor 110 can initiate an error protocol, which in some embodimentscan produce one or more displays of information to the user, such as anerror message, as shown in block 360, or information about the propertype of sensor 120 and/or cable to be used with critical-care patientmonitoring system 100, and/or the proper way to attach a sensor 120, asshown in block 370; and/or the error protocol can clear and/or disablethe display of physiological information from the patient on thecomputer display 280, as shown in block 380, since such informationmight be incorrect or unreliable if the gatekeeper signal orverification signal is determined to be incorrect.

In some embodiments, the computer processor of the computer monitor doesnot utilize the gatekeeper electrical signal to process, analyze,calculate, or obtain any patient information from thepatient-information electrical signal or signals or from any othersource; rather, the patient information contained in thepatient-information electrical signal is independent from and is notrequired to be calibrated, adjusted, or modified by the gatekeeperelectrical signal.

When the gatekeeper electrical signal represents a simulated temperaturevalue, but not an actual temperature value, the computer monitor can insome embodiments receive such gatekeeper electrical signal as an actualtemperature value and proceed to function normally and display patientdata in a normal manner, as though the gatekeeper electrical signal wereproduced using an actual temperature value. Since the gatekeeperelectrical signal is not normally utilized to calibrate, modify,normalize, or adjust the patient information in the patient-informationelectrical signal, the simulated temperature value of the gatekeeperelectrical signal may not affect the accuracy of the patient data. Thus,the same computer monitor can be configured to function properly, insome embodiments, with a patient sensor that is configured to produce agatekeeper electrical signal using an actual temperature measurement ora patient sensor that merely produces a signal with a simulatedtemperature.

The invention claimed is:
 1. A disposable patient-monitoring devicehaving first and second wires and configured to be attached to tubing influid communication with a patient's blood vessel, and configured to beattached in electrical communication with a medical device, thepatient-monitoring device comprising: at least one pressure sensorconfigured to be in fluid communication with the patient's blood vesselthrough a fluid-receiving region in the pressure sensor and configuredto be in electrical communication with the medical device using thefirst wire, the pressure sensor being configured to sense a pressurewave in the patient's vasculature and being configured to transmit, withthe first wire, at least one patient-information electrical signal thatindicates a physiological parameter of the patient to the medicaldevice; and a temperature signal generator that is configured to send agatekeeper electrical signal to the medical device from the disposablepatient-monitoring device with the second wire, to enable the medicaldevice to confirm that the patient-monitoring device is attached inelectrical communication with the medical device, the gatekeeperelectrical signal not including diagnostic or physiological informationabout the patient; wherein the gatekeeper electrical signal is notconfigured to be used to modify the physiological parameter conveyed bythe patient-information electrical signal in order for thepatient-information electrical signal to indicate the physiologicalparameter of the patient; and wherein the temperature signal generatordoes not receive information from the pressure sensor.
 2. The disposablepatient-monitoring device of claim 1, in combination with the medicaldevice.
 3. The disposable patient-monitoring device of claim 1, furthercomprising a housing.
 4. The disposable patient-monitoring device ofclaim 3, wherein the device is configured to measure an actual ambienttemperature.
 5. The disposable patient-monitoring device of claim 4,wherein the ambient temperature is measured inside of the housing. 6.The disposable patient-monitoring device of claim 4, wherein the ambienttemperature is measured outside of the housing.
 7. The disposablepatient-monitoring device of claim 1, wherein the gatekeeper electricalsignal is generated by a simulator, not an actual temperaturemeasurement.
 8. The disposable patient-monitoring device of claim 7,wherein the device does not include any temperature sensor.